How do I record audio input on my Mac via 3.5mm jack?

I am currently setting up a recording setup for my church, we are using rca output on an allen & heath gld80 mixing board. We are using an rca to 3.5mm jack adaptor for output. The board is configured correctly to my knowledge, but I can’t figure out how to capture audio from the headphone jack in obs. The macbook being used is a macbook air with an m1 chip. Thanks in advance for the help.
 
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